1. Field of the Invention
The invention relates to a cell plate assembly for growing cells or tissue cultures in vitro and includes inserts for supporting cells or tissue cultures in a fluid medium that contains nutrients to promote the cell or tissue culture growth.
2. Description of the Related Art
Multi-well plate assemblies have been developed for growing cells or tissue cultures in vitro. The typical multi-well plate assembly includes a well plate with a plurality of wells for containing a fluid medium that has nutrients to promote the cell or tissue culture growth. The multi-well plate assembly further includes an insert plate configured to nest with the well plate. The insert plate includes inserts, each of which has an open top and an open bottom. A porous membrane extends across the open bottom of the insert and is formed from a material that permits the diffusion and transport of ions and macro-molecules across the membrane. The insert extends sufficiently into the well to communicate with the nutrient-rich fluid medium in the well. Thus, a cell layer can be attached and grown on the membrane and can receive nutrients through the microporous membrane from the fluid medium in the well.
The wells must be accessed periodically for adding or removing fluid. This access typically is achieved by access ports that extend through the top wall of the insert plate at locations aligned with the respective wells. The access ports are dimensioned to receive pipettes so that the level of the fluid medium in the well can be adjusted or so that portions of old medium can be aspirated off without removing the insert plate and without contacting the cell or tissue culture that is being grown on the membrane of the insert. Examples of multi-well plate assemblies are shown, for example, in U.S. Pat. Nos. 5,652,142, 5,801,055 and 5,972,694.
Multi-well plate assemblies typically are manufactured with certain standard external dimensions and with certain standard numbers of wells to ensure compatibility with laboratory equipment. One industrial standard includes 96 wells arranged in an 8×12 rectangular matrix. The laboratory equipment includes robotic pipette devices for automatically entering the access ports of the insert plate to adjust the level of fluid in the respective wells. The design of the micro-well plate assemblies should facilitate the robotic insertion of the pipettes into the access port. Thus, both the inserts and the access ports should be as large as possible without exceeding the required center-to-center spacings of the wells and without permitting contamination between the cell or tissue cultures being grown in the inserts and the pipettes being inserted into the access ports.